Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[French, jerk, jolt, from Middle French, from Old French dialectal saquer, to jerk, pull, variant of Old French sachier, to pull forcefully, turn over, shake up, from sac, sack (perhaps in reference to the shaking of bags of wheat to settle their contents); see sac.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From French saccade.

Examples

That can be attributed to something called a saccade—a fast movement of the eye that lasts between 20 and 200 milliseconds.

Words that are more generic or abstract

Wordmap

Word visualization

Comments

Derived from a French word for twitch, saccade is a typical occurence in visual perception — the eyes fixing on one point after another in the visual field. Humans and other animals do not look at a scene in a steady way. Instead, the eyes move around, locating interesting parts of the scene and building up a mental 'map' corresponding to the scene. (From ArtLex)

"I gain the crest of the hill and there it is, falling away behind me, swags and ruches of greenery and brick, under the blue-painted ceiling of its recent conversion: New London, city of the toppermost property prices. I can see a golden drop of sunlight on the glans of the Swiss Re Tower (Lord Foster's phallus, commonly known as the Gherkin), and the inverted pool table of Battersea Power Station. I can see the Hampstead massif and the Telecom Tower. I can see my life, entire, in a single saccade."

Wiktionary's definition (n. music - The sounding of two violin strings together by using a sudden strong pressure of the bow) is in a way misleading. A saccade is not necessary for double stopping - if it were several serene examples of violin writing would become unbearable. Triple stopping is another thing, as it it impossible to achieve without this technique. The Brahms violin concerto affords many examples.